Life at the Cellular Level Flashcards
What is the difference between passive and facilitated diffusion?
Both require concentration gradients but facilitated diffusion requires carrier molecules.
Subject to certain criteria, in passive diffusion the molecules pass freely over the plasma membrane
What is endocytosis?
cell membrane invaginate to take in extracellular materials
What is exocytosis?
cell produces vesicles to carry internally made proteins to transport them out of the cell.
What does an occluding junction do?
seals gap between epithelial cells
What does an adherens junction do?
connects actin filament bundle in one cell with that in the next cell
What does a desmosome do?
connects intermediate filaments in one cell to those in the next cell
What do gap junctions do?
allow for communication between cells by allowing passage of small water-soluble molecules
What do Tight junctions do?
create a physical barrier to diffusion across layers of cells
What is the name of the protein that forms the pores in the outer membrane of the mitochondrion?
porin
What form is mitochondrial DNA in?
circular
What does the nucleus contain?
DNA, nucleoprotein and some RNA
Where is the site of ribosomal RNA synthesis and ribosome assembly?
nucleolus
What does the rough endoplasmic reticulum do?
has ribosomes attached
protein modification and transport
What does the Golgi Apparatus do?
protein modification and transport
What does the smooth endoplasmic reticulum do?
breakdown of compounds such as drugs and glycogen
synthesis of lipids
What do lysosomes do?
separate enzymes from the rest of the cell (will be used to digest engulfed particles or cells own materials)
Name some of the main functions of the cytoskeleton.
- is the cell’s painter and decorator’s
- supports and maintains cell shape
- holds organelles in position
- moves organelles
- involved in cytoplasmic streaming
What are the 3 parts of the cytoskeleton?
microfilaments
intermediate filaments
microtubules
What are microfilaments?
made up of strands of the protein actin
interact with other strands of proteins
What are intermediate filaments?
made up of fibrous proteins that arrange themselves like ropes
stabilise cell’s structure and help maintain its shape
What are microtubules?
long, hollow cylinders made of tubulin
